Heretofore known working machines include a wheel loader as described in JP-A 8-40223 (1996).
This wheel loader comprises a front machine body having front wheels, and a rear machine body having rear wheels. The front machine body has a working device, and the rear machine body is equipped with an engine and a HST (hydrostatic transmission).
The working device has a lift arm which is free to rock up and down, and a bucket disposed on the front-end side of the lift arm for free rocking motion. Instead of the bucket, another attachment can be fitted to the front-end side of the lift arm.
The HST has a HST pump constructed of a swash plate-type variable displacement pump which is driven by an engine, and a HST motor which makes a closed-circuit connection with the HST pump via a pair of speed-change oil passages. The HST motor is driven with oil discharged from the HST pump, and, the rear wheel is driven by rotational power output produced from the HST motor. By making changes to the angle of the swash plate of the HST pump, it is possible to vary the discharge direction, as well as the rate of discharge flow, of hydraulic oil discharged from the HST pump, and thereby permit forward or backward movement of the wheel loader while varying vehicle speed in a stepless manner.
Moreover, the wheel loader has an accelerator pedal. Through the depressing operation of the accelerator pedal, engine rotational speed is controlled, and, as the engine rotational speed is changed, a control pressure for the control of the swash plate of the HST pump is varied. Vehicle speed is controlled on the basis of the engine rotational speed and the control pressure for the swash plate.
In addition, the wheel loader has an inching pedal for decelerating and stopping the wheel loader. The inching pedal is designed to reduce the angle of the swash plate of the HST pump when it is stepped on, for allowing deceleration and stop of the wheel loader.